First we Subtract.
[tex] \\ \frac{3*4}{7*4}=\boxed{ \frac{12}{28}} \ and \ \frac{1*7}{4*7}=\boxed{ \frac{7} {28}}.
Subtract:[tex] \\ \frac{12}{28}- \frac{7}{28}=\boxed{ \frac{5}{28}} [/tex]
Now we have 5/28y=1/2.
Subtract both sides from 1/2.
[tex] \\ \frac{5*1}{8*1}=\boxed{ \frac{8}{1}} \ and \ \frac{1*4}{2*4}=\boxed{ \frac{4}{8}} [/tex]
y=[tex] \frac{4}{8}[/tex]